Polymeric ultraviolet light absorbers are especially desirable in thin films of between about 0.05 mils and about 0.5 mils since monomeric absorbers are readily lost by diffusion, and solvent leaching because of the high surface area in relation to the volume of material employed. The preparation of polymeric UV-absorbers usually involves the vinyl polymerization of substituted UV-screeners such as (2-hydroxy-4-methacryloxybenzophenone) or the condensation polymerization of properly substituted UV-screeners such as 2-hydroxybenzophenone-4,4'-dicarboxylic acid with glycols or 2-hydroxy-4,4'-bishydroxymethyl benzophenone with diacids.
It has now been discovered that improved polymeric films can be formed from a melamine nucleus compound, a benzophenone and preferably a polyol. Moreover, the benzophenone appears to be incorporated in the polymer as indicated by long term thermal aging tests, which renders the transparent coating ideally suited for protecting transparent polycarbonates, and other UV degradable materials.